


Mermen don't exist.

by Anihan (Nakagami)



Series: A series of AUs. [2]
Category: Sherlock (TV)
Genre: A LONG snippet okay?, Alternate Universe - Mermaid AU!, Ask me about their backstories, Beware Computer Nerd Humor, Contains a C++ Joke, Fluff, Holmes brothers work together!, Just a snippet, M/M, Navy John, Shaggy Dog Story, Soooo much fluff, i dare you
Language: English
Status: Completed
Published: 2013-07-31
Updated: 2013-07-31
Packaged: 2017-12-21 04:54:17
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,169
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/896031
Author URL: https://archiveofourown.org/users/Nakagami/pseuds/Anihan
Summary: <blockquote class="userstuff">
              <p>What aquatic creature is approximately five feet long, possesses both dark scales on his back and pale skin on his belly, has fins and a full head of long dark hair, and has a dolphin-like tail? </p><p>Sherlock of course, and his brother Mycroft is only a few inches longer. They are all a bit shaken up when two humans get brought out to sea by the tides. The first one was easy to rescue on his own - kind of short, wasn't he? Not much bigger than Mycroft - but the second one was longer, heavier, and a bit grey at the temple. </p><p>Hm, Mycroft thought to himself. Maybe I should keep them. </p><p>Sherlock had much the same idea.</p>
            </blockquote>





	Mermen don't exist.

**Author's Note:**

  * For [Hara Peko](https://archiveofourown.org/gifts?recipient=Hara+Peko), [fanomy](https://archiveofourown.org/users/fanomy/gifts), [Kinah_Jala](https://archiveofourown.org/users/Kinah_Jala/gifts).



  
It is difficult to speak underwater... that is, with verbal definitions of 'speak'. You will therefore have to imagine Sherlock's expressions, gestures, and the multitudinous water-borne hormones telegraphing his urgency when he stormed his brother's coral office reef, 'screaming', «Brother, there's another! Brother, _Mycroft!_ There's a second body at the gates!»

«And now the whole ocean knows,» Mycroft hissed shortly, closing his notes with what would have been a sigh in open air. It was more like an annoyed gurgle.

«Of course they do. Anyone within a kilometer of the Gate received the missive, as you would have noticed as well if you had been paying the _slightest_ attention to anything but your feast,» he sniped, gesturing to the underwater version of paperwork: Reef work.

«Implying that I am a workaholic and also capable of eating anything: How original.» 

Sherlock rolled his eyes but Mycroft cut him off with a complicated series of angry gestures, all of which somehow translated into a sort of intense grumbling. «Hurry and get a net and your lock picks, then. If he's like the first human then he will need our help getting free of the Gate's pull. He might drown if you wait, and _what_ will you do _then_?»

Mycroft's voice showed just how uninterested he was in this endeavor: It implied sarcasm where his words implied an actual tragedy. Sherlock bristled and swished his tail in a show of dominance, crowding close to his brother's side but Mycroft didn't cower; It was his turn to roll his eyes at his brother's antics.

The younger merl backed off with a short huff. «Which is why I've come to you, brother dearest, with both items in hand. Now let's _go!»_

«Yes, fine, let's go, not like I don't have important time-sensitive work to do here...» But despite the implied reluctance, they went.

The need for Mycroft's help quickly became apparent. This second human was nearly twice Sherlock's size, all broad shoulders and rugged good looks. The man was unconscious and _long_ , possessing of a deep sailor's tan and rich, thick dark hair, although the color was indeterminate at this point. Mycroft felt something flicker inside at the sight of him, something that might have been _interest_. He marveled at the sensation.

The human's body was stretched out along the length of the Seafarer's Gate as if it were a Saint Andrew's Cross, held primarily upright with all limbs extended. He was alive - which was lucky for him, thirty feet underwater and existing without gills. This Gate probably liked him, which was just as well: It pulsed with oxygen, skin-permeable and rich with nutrients. As long as his body temperature was kept up, which it was, another gift of the Gate - so it must  _really_ like him - the human male could survive here until a rescue by non-human hands could be staged.

And here the two young merls were, ready to stage that rescue. Mycroft came forward first, disentangling the man from the coral that composed the Gate- «With no locks! The Gate kept him with no restraints at all!» the youngest merl marveled - and then carefully lowering him into the net Sherlock held open.

The first brush of skin on skin set Mycroft's mind tingling. The dignitary reeled. The human's name, written on his unprotected mind, burned on Mycroft's lips: _Detective Inspector Gregory Lestrade._ A flare of protectiveness riled through his body with a soft gasp, and he fumbled with the netting in his hands before regaining purchase and grasping it tighter.

«His mind is unprotected, he has no barriers at all.» Mycroft could hardly keep the excitement from tinging his thoughts, but he managed somehow to regain a stately appearance. «We can speak to him, Sherlock. We can finally learn their language!»

Sherlock, having no such compunctions about proper public behavior, positively wriggled in delight. «His mind isn't unprotected, it's _open,_ deliberately kept completely free! No wonder the Gate approves of him: He's a peace-keeper, a pure soul!»

The young merl circled his prize in loops of unadultered joy. He pressed the lower right side of his face against the man's neck, scenting him, marking him. The older merl couldn't deny that the two of them made an attractive picture, and another burst of unexpected protectiveness shot through him. _I want this,_ he thought, and the response was as welcome as it was an absolute surprise. One brush of their minds and yet already....

Sherlock broke into his thoughts with a particularly apt deduction. «We could keep him, if he consents. He could _stay.»_

Mycroft's eyes fell closed. He shoved away the desire for that future with the force of years of disciplined practicality: «Don't make that sort of decision on your own, brother dear.»

Sherlock moved back to allow Mycroft to scent the creature as well, marking this _Lestrade_ as their... guest. «We _are_ saving his life. His kind believes in returning the favor, you can see it right there on his mind. He'd stay if we asked him to.»

They both knew that merely having the human nearby wouldn't be enough, that interaction and reciprocation would have to be achieved, but the thought was both as touching from Sherlock as it was rare. 

Mycroft sighed but, truly, the little one's enthusiasm was infectious. And who was he to deny the allure of the human stretched out before them? «If he offers a favor as thanks for our saving his life, _then_ you might be free to ask that of him, but do not presume to know his mind. Especially not now. Come, let us get him to my cove. The other one should be awake by now.»

The 'other one' was.

It wasn't an hour later that the two were dragging _Detective Inspector Gregory Lestrade_ 's limp body into a neat cliffside inlet deep inside the Holmes Archipelago, past the beaches and the islands to a set of four structures that made up a secluded cove. The first human - whose mind was locked tight and who went by the name of John, if the badge they could now read on his shirt was any indication - was drying his clothes on the rocky beach and hanging about in his pants. He let out a startled cry and jumped to his feet. The two merls worked side by side to bring their burden closer as John came out to meet them.

"Oh thank God," John gasped, running forward until he was thigh-deep in the tepid water of the cove, and clasped the sodden man to his chest, practically sobbing in pain mingled with relief. "Thank you," he cried, and the two merls allowed him to bring the man ashore without interference.

Lestrade was still unconscious. John dragged him closer to land until it was necessary for him to pull the man's dead weight over his shoulders in a firemen's carry, grunting to bear his water-laden weight but still able to lay him on the solid ground further inland. The merls came as well, shameless in their curiosity, as close to the land as was possible without becoming beached or growing legs.

"Don't be dead, God, please, just let him live," John plead, and Someone must have been listening because the man, although pale and somewhat limp inside the netting, still had a pulse.

The mermaids watched with varied fascination - only the elder's being wary - as the blond man puts his lips to those of his two-footed companion, resolute in his purpose, and after a ritual of chest-beating and repetitive chanting, the older human male appeared to come back to life.

This, of course, was good fodder for rumors of the legendary Kiss of Life belonging to humans.

Gasping and coughing like an asthmatic at the end of a marathon, Lestrade just let the world continue on without his input. He sat up with John's help and clutched desperately at John's hands on his chest, laughing a bit in frantic relief. John leaned into Lestrade bodily and sobbed joyfully into the man's hair, glad for the moment, just being thankful for not being alone.

The humans pulled themselves together fairly quickly, all things considering. Both of them snapped into action as soon as Lestrade started shivering, John quickly helping Lestrade strip off his rescue net and sodden clothing, and they dried him off as much as possible using John's. Now they were both in only their pants.

The merls were too far away to hear the murmured conversation properly, and that was positively unacceptable to Sherlock now that they could finally understand human words. With Lestrade fully conscious the entire lexicon available to _him_ was now free range to _them_. The younger mermaid made a low sort of trill, almost like a horse's whinny of interest: It was a desperate sound, almost salacious, and the older merl shot him a dirty look as if to say, "Really, brother? In public?"

But Sherlock didn't care. He circled closer to the shore and whined at the back of his throat like a dog, whimpering and pleading with his wide irridescent eyes begging for their attention. The two humans clutched at each other and pant laughingly, again just like dogs, reveling in being alive. They're too busy petting at each other and thanking respective deities to pay much attention to their rescuers.

«Sherlock, just leave them alone! Lestrade was recently half-dead and John's only just brought him back! Let them get over their ordeal before your enthusiasm pushes them to death by exhaustion.» Or exasperation, Mycroft thought but didn't say.

Wise words, but Sherlock had had enough of being blatantly ignored. He let off the whining for an attempt at proper verbal speech, an attempt that was, more or less, a hearty success. "Lessssktradt. Jawuuun!"

"Jesus!"

"Christ!"

"It talks! It just said my name-- it just said-- it _knows our names!"_

Then the two men glanced at each other. Suddenly, they were teenagers again, and one had a twinkle in his eye. This twinkle was a joker. It wanted to lean over and nudge his companion's shoulder and say, _"H_ _eh, you said Jesus, I said Christ, someone should finish that off with 'Vampire Hunter' or 'King of the Zombies' or something,"_ but it instead merely winks at the answering twinkle in Lestrade's eye that's thinking _the exact same thing._

But never let it be said that the two men (overgrown teenagers) were not adventurous. (And stupid.) It was Lestrade who stood and came to the water's edge on the other side of the cove where the drop from land to ocean was steeper and crouched there. Sherlock swanned over to meet him, bobbing his head over the surface a mere three feet out from the rocks.

"Christ, you're a tiny thing! I mean. Er, hi. Thanks for saving our lives, and all that. We're not just a convenient food source, are we? Cause I'd like to know now if we are so that I can prepare for my dashing escape."

The other one, the blonde, John, made a high pitched snorfle at that; Sherlock correctly identified the noise as an airborne gigglesnort - the sound was necessarily different above air compared to when underwater - but the human had made more than a passing attempt at stifling that reaction before it could reach open air. Sherlock mimicked it for curiosity's sake, just to see if he could, and four bushy eyebrows went skyward when he correctly copied the sound. The resemblance was uncanny.

"So. Right. That was creepy." Lestrade shuffled around until he was kneeling - on actual knees! - and leaning a bit over the water. "So... you like mimicking people, huh? Can you at least understand me?"

John had come up behind him. He looked worried and amused in equal measure, the expressions curiously the same even the across species boundaries. "Greg, I don't think they communicate like we do. Look at them move, it's almost like a dance, like bees do. I don't think I could pull off anything half as graceful, much less... in the water," he finished lamely.

"Yeah yeah, sure..."

If Lestrade had wondered why John had hesitated at the end of that sentence the copper didn't verbalise the thought. The older man was too busy leaning precariously over the edge of his perch and trying to get a good look at the second mermaid to pay John much attention, although he really should have. Especially when John snapped, "Careful! If you drown after mussing up my best jeans--"

The sentence was never finished. Sherlock had gotten bored of not being part of the conversation ( _Again_!) and had reached out with one hand - just one!  _Christ_ , these mermaids are strong! - and yanked Lestrade back into the water.

He floundered instantly.

"Oh for fuck's sake."

John groaned at the same time as Mycroft growled a similar sentiment. Both exclamations come out as a sort of dissatisfied burble as both of them were busy leaping forward to rescue the human again, this time from Sherlock's curious claws.

Mycroft hissed. «I thought you wanted to keep him, Sherlock!»

«I _do_!»

«They don't keep well once dead!»

Mycroft snapped with actual teeth involved, and Sherlock backed off with a short hiss. Lestrade fell against Mycroft with a soft exclamation but the merl embraced him eagerly. Quite eagerly. The action brought their minds immediately into contact and Mycroft, the only one of the pair with a mental shield, practically thrummed at the effort it took to keep their minds separate. The pure soul was frightened but Mycroft nuzzled his face to calm him, reveling in feeling the grit of human hair there, and then swam the human closer to where John could support more of his weight.

"I--well--that's--... Well, that's certainly nicer than the first time I went overboard today," Lestrade remarked with a blush.

Mycroft smirked.

The blonde, however, was furious. "You're banned from the water. Forever," he snapped. He accepted Mycroft's assistance without any resistance - aka: put Lestrade on the mermaid's back and then merely provided balance as they swam back to shore. "Thanks," he added to Mycroft, who acknowledged the thanks with a deep purr, causing Lestrade to shiver. John quirked a smile. "Not that he's remorseful at all, the git."

"What was that, John? Banned from watersports, am I?" Lestrade snarked with a teasing little grin. His heart was pounding in a way that had absolutely nothing to do with fear. "Didn't know the Royal Navy had that sort of doctor on call."

"A doctor!" Sherlock shrieked. Aloud. The humans jumped, knocking Lestrade askew, but Mycroft held tight.

John'd just finished getting Lestrade settled again when Sherlock redoubled his efforts to examine the land mammals up close. The young mermaid was swimming circles around the trio, nearly tripping Mycroft and actually tripping John, somehow, _underwater_ , which truly was a feat that deserved an award of some kind, even as it sent the doctor's head under the waves with a startled, "Oi! Blubbub...bub...b..."

Unlike the _Detective Inspector_ , the doctor could swim. Quite well, in fact, which was to be expected of a naval doctor. And the world introduced from below the water... it completely blew his mind.

The world...  _this_ world was an entirely different place.

You could see _everything._ The land on shore and the land beneath the sea-- even the sky was glorious from this position. The sun shone down like a beacon at high noon, a place of refuge for when John finally managed to _stay_ on dry land and needed to get warm. But that would be a minute. John was too busy staring  _at_ the surface to care much for getting above the surface himself.

The view from under the water was just too beautiful to contemplate from afar. 

Mycroft's body was a work of art; he held fast to the human along his back, lithe and small and with no signs of tiring, and, gods, how _tiny_ these mermaids were! Sherlock was a mere four feet at the shoulder, Mycroft just under five, and their slim bodies were scaled from mid-chest down. The two merl shared a color scheme, darker reds and browns along their backs, pale greens along their bellies the same color as their eyes. If you looked closely, their back scales might even match the shades of their hair. But their faces, necks, chests... it looked so similar to human skin...

«Jauun.»

John closed his eyes and sighed deeply, letting the air out of his lungs so that he could stay below the surface a moment longer. When he opened them again Sherlock was directly in front of him, swaying with the sea's current.

_God, these mermaids are gorgeous!_

Sherlock preened at the comment, once again reading it directly from the human's mind - or so John thought, although the merl could easily read his appreciation in John's body language, and Sherlock reached out eagerly to grasp the human's hands in his own talons. The human pulled the merl closer, staring down at the inhuman hand in his in blatant fascination. It was scaled, yes, five-fingered with fine, pale little scales that matched the tone of John's palm although they covered both the entirety of Sherlock's hands and forearms like socks.

«You'll stay, won't you?»

John flinched back and glanced up. Sherlock was staring at him with those wide, earnest eyes - yes, definitely the color of the merl's underbelly - but John was speechless before him. The mermaid could learn his language, possibly, but there was no way for John to learn Sherlock's tongue in return. _I'm sorry_ he mouthed regretfully, and the merl's face dropped.

The young mermaid nodded slowly. He could understand the need for time, for patience, with a decision this large. «I can wait,» he confirmed, and John's eyes went wide again with surprise.

Tan skin and pale scale wrapped together in ways a child grasps fervently for its mother, the way its mother holds on just the same; like a scientist and his perfect experiment interlocked in a duet, although neither of them could sing. There was a depth here to Sherlock's yearning that he didn't know how to answer, but John tried. He wouldn't let go.

They stayed below the surface for as long as John could, giving up on remaining there only when it became too painful to continue holding his breath.

Sherlock didn't wait for his companion to swim for air on his own with his pitifully inadequate skill at moving through water. The merl shot upward at the man's behest, holding him close to his body as they broke water. The human gasped upon reaching the surface and, although he didn't need to, Sherlock followed suit, gulping in the air greedily at his side. In this, at least, he was able to feel one step closer to the man already.

The other duo hadn't wasted time waiting for them. Somehow the mermaid had managed to communicate _Don't worry, Sherlock won't let him be hurt_ without verbal speech, not that Lestrade could spare a moment to be worried for John when the man was, oh, about ten _thousand_ times better at swimming than he. The human took his blessings that _one_ mermaid wanted to spare their lives: The rest of this ocean was a wildcard.

(It may have helped that the water was clear enough that you could still _see_ John and Sherlock. It didn't look like Sherlock was keeping him there, and John didn't seem distressed, so Lestrade didn't worry about him.)

Lestrade now sat in the shallows with the water at his waist, leant back against the rocks. Mycroft had taken the opportunity to examine him up close, peering into ears and crevices and trilling with satisfaction at every feature he correctly deduced were the same across their species divide. (There were more similarities than not, he was glad to find.) The copper brushed him away frequently when he became too friendly, but the merl came back seconds later to get a second look. And a third look, and a fourth, a catalogue of all the things that this _Detective Inspector Gregory Lestrade_ was and could be.

«Are you a father?» he asked, but the human gaped at him - as if he were unaccustomed to the feeling of a touch on his mind, a fact corroborated by the high flush in his cheeks - and didn't answer. «I suppose you can't understand me then. How disappointing.»

And it truly was. A painful urge had built deep within Mycroft to bring this human closer, tighter, and to release him if and only if he begged for freedom. He wanted him; he yearned for him, he _longed_ for him. The species barrier was of no consequence - A merl is a being of magic and sea, potential infinite: One's race is never of any consequence to them - but a language barrier was a true tragedy that would be difficult to overcome.

"Hey doc," came Lestrade's voice, a bit panicked. The navy man looked up from the water and immediately had to hide a grin. Lestrade was looking about wildly for an escape. "I think this guy's gonna eat me. Or dissect me. Or something equally heinous."

"Oh, you studly creature." John, to whom Mycroft's words were ringing in his ears with frustration, failed at keeping a straight face. "I think he likes you. Awww, that's adorable! You've got yourself an admirer," he cooed, abandoning his deadpan expression for a smirk. 

Alarmed, Lestrade squeaked, "What?!" He scrambled to his feet, much to Mycroft's disappointment - or not, as it put Lestrade's anatomy in a new position for Mycroft to further examine - and hurried back to shore, much to the chagrin of both mermaids.

The detective was still spluttering when John joined him on the rocky beach. "Just give me a minute to talk to him," he told Mycroft, who hummed acquiescence and mournfully swam back to his brother. John watched the two of them communicate again with fascination. Sherlock, despite his own sudden rapport with John, had welcomed Mycroft close the instant he showed distress, curling tight around his brother's body - because John was pretty sure they were brothers judging by the color schemes - and soothing him as much as he was able. They were close, John could tell, but how much of that was want and how much was necessity out here in the sea?

"You're not as freaked out about this as I am," Lestrade accused. John hummed. "Why aren't you as freaked out about this as I am?" 

"Well..." John hemmed, but he caved when Lestrade's expression went from raincloud to thunderous. "They saved you."

"For food." The detective's expression went from alarmed to horror in a flash. "Or breeding stock. Or... oh god, what if it's both?"

Twin hisses came from the water-- causing Lestrade to laugh somewhat hysterically and John to jump --but the perceived show of aggression was disproved by their facial expression: It appeared the mermaids were laughing at them. John gave a small smile. "Yes, well. They saved you because I asked them to, so I'm quite inclined to thank them instead of criticize their diet."

A pang of regret hit the copper right in the heart. Lestrade blushed beautifully, a comment John said aloud, causing the blush to deepen.

Once he'd realized his mistake he took no pleasure in postponing his acknowledgement of it: "Sorry," he called out to the ocean critters. "Panicked. Not an excuse, but don't take it out on me, please. I didn't mean to hurt ya, little guy."

Mycroft snorted water. He remained just beneath the surface with Sherlock twined around his body, hanging off of him. This pose looked regal, practiced; the duo looked formidable as a team, possessive. «Would you please inform the Detective Inspector that we are of an age, taking into account variation between our species. We are all adults here.»

John snorted with amusement. "Hey, Greg? The mermaid says 'shut up, I'm just as old as you are'. But nicer. Actually, they're both really sort of posh for merls. I've never met any as refined as you," he added to the mermaids themselves. "And I've never had any of them try and _speak_ to me before."

'Greg' - no, Lestrade suited him better, Mycroft thought, and mentally corrected it back to his last name - spluttered and looked even more flustered. "Uh, in case you hadn't noticed, _Watson,_ they're talking to us right now. Or something. At least I think that's speech: It certainly sounds like a language, but you know me, it isn't like anything I've ever heard before. Except maybe Linux. Or a computing code or something drastic like HTML. And _wait just a goddamned_ minute, how do _you_ speak _merman?"_

Again, John snorted, this time derisively. "Mermen don't exist, Greg. The correct term is still mermaid. Besides," he interjected like a court jester rearing up for a punchline, both eyes rolling in exasperation. "What self-respecting sailor hasn't studied Sea Plus Plus?"

**Author's Note:**

> Feedback welcome.


End file.
